Despite tramadol’s popularity as an oral analgesic in veterinary medicine, experts have debated it’s efficacy for years. And a new study has added fuel to the fire.

Researchers at the University of Georgia found that tramadol was ineffective in relieving pain associated with osteoarthritis in dogs.

The researchers compared the use of tramadol with both placebo and nonsteroidal anti-inflammatory drugs (NSAIDs) in 35 dogs with osteoarthritis of the elbow or knee in a randomized, blinded, placebo-controlled crossover study.

“The data shows conclusively that tramadol is not an effective drug in treating the pain associated with arthritis in the dog, despite its common recommendation,” said lead researcher Steven Budsberg, DVM, MS, DACVS, professor of surgery and director of clinical research at the University of Georgia College of Veterinary Medicine. “This use of tramadol is a classic example of failing to acknowledge and control for bias when evaluating a potential treatment.”

That seems pretty conclusive. So why do so many veterinarians still prescribe tramadol for their patients?

NEWStat reached out to Ralph Harvey, DVM, MS, DACVAA, for comment. Harvey, an associate professor of anesthesiology in the Department of Small Animal Clinical Sciences at the University of Tennessee College of Veterinary Medicine and a coauthor of the AAHA Anesthesia Guidelines for Dogs and Cats is an expert on pain management.

When he speaks about pain management at continuing education seminars, Harvey says he always asks the participants how many of them have heard experts discredit tramadol. “I have a lot of people raise their hands,” he says. Then he asks how many of the participants are prescribing tramadol. “And I see the same people raise their hands.”

Harvey acknowledges that the debate over tramadol is an old one, but says the issue is complicated by the fact that tramadol, like gabapentin, is adjunctive medication: “It’s not intended to be used as a primary analgesic, as the [other] opioids or the NSAIDs might be used.” He says that typically, a veterinarian would administer an NSAID first, then use tramadol as a supplement to complement it. “The combination provides a greater level of efficacy than would the single use of the NSAID by itself, and certainly [more than] the single use of the tramadol by itself.”

Harvey says the study’s research methodology is very appropriate for osteoarthritis pain, but he has reservations about its scope. “My impression is that it may not deal with, recognize, or be sensitive to the affect of pain.” By ‘affect,’ Harvey means the emotional component of pain, which he considers a very important part of the pain puzzle.

“[And the emotional component of pain is] exactly what tramadol may target, but it’s so difficult to measure,” Harvey says. “Our greatest limitation in dealing with pain and the study of pain is not in the pharmacology, it’s in our ability to recognize and quantify pain and analgesia.”

That’s important, Harvey says, because the emotional component of pain is what gets in the way of our willingness to engage with life. “And we really want our patients, our dogs and cats, to engage in life, to engage in the human-animal bond. If they’re suffering, if they have that emotional component of pain, they’re not going to be able to engage in life. They’re not going to be able to love us.”

And he notes that it might be easy to misinterpret the study’s findings: “What we have here is the absence of evidence that tramadol contributes to the relief of pain. We don’t have any kind of proof that it doesn’t work. We have a lack of evidence that it does work.”

That’s an important distinction. And one that may explain why so many veterinarians still prescribe tramadol.

Harvey also notes that other factors are at play in addition to the debate over efficacy, including the current opioid crisis and the growing problem of people abusing tramadol that’s been prescribed for their pets. “In a climate where we have now recognized potential for diversion, that influences our enthusiasm for using tramadol. But I don’t think we’re ready to write it off.”

Harvey says he would continue to use and prescribe tramadol, but as a supplemental analgesic. “And I encourage veterinarians to consider using it.”

Because if it does address that emotional component of pain, it’s something we need in our toolbox.

“Because something to get the animal engaged in life again is important. We send our animals home on an NSAID so that they’ll be able to walk around. But we also send them home on something to address the affect of pain, so that they’re interested in life again, [and want to know] where’s the cat? And what are the kids doing?”